The development and characteristics of narcotic-binding receptors will be examined in the brains of perinatally-addicted mice. The possible role of changes in protein synthesis and catecholamine metabolism in sensitization to the stimulant effects of morphine, cocaine and amphetamine will be explored in mice that have been pretreated with each of these drugs, respectively. A genetic analysis will be carried out on sensitization to these drugs, as well ason the mode of inheritance of narcotic receptors in mice. Genetic studies will be carriid out with recombinant-inbred strains and congenic lines derived from purebred strains BALB/Cby and C57B1/6By. The metabolism of morphine in perinatally-addicted mice will be assayed both in vivo and in vitro. BIBLIOGRAPHIC REFERENCES: Shuuter, L., Webster, G.W. and Yu, G. Increased running response to morphine in morphine-pretreated mice. J. Pharmacol. Exp. Ther., 192, 64-72 (1975). Shuster, L., Webster, G.W. and Yu, G. Perintal narcotic addiction in mice: sensitization to morphine stimulation. Internat. J. of Addictive Diseases, 2, 277-292 (1975).